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Topic: fermentation (Read 12929 times)

Your comments on waste products is fascinating. I had never pondered the difference in waste composition depending on bacteria/yeast state of being and phase of lifecycle - and that impacting crust flavor. Would be a very interesting set of trials to make batches of doughs with normal, stressed, happy, dividing, stagnant organisms and do blind taste tests to see exactly how and to what extent these can be tasted by humans in finished pizza crust.

On the temperature/replication/metabolism bit the picture does seem more complicated than I originally assumed and I appreciate your pointing out where my assumption was too simple. You also make a very good point that a simple temperature vs. growth curve made for an organism alone in media does not apply very cleanly to that organism when it is in a culture with another organism in a symbiotic relationship.

However, I still feel it is counterintuitive than when I get a higher concentration of one beastie in a mix, I will not see a higher ratio of its namesake waste product. Perhaps an answer is that the dominant constraint on L. Sanfranciscensis is not temperature, nor sufficient population, but nutrient availability. If the yeast rapidly consume nearly all the nutrients themselves like lordly masters, then dole out meager allocations of maltose to keep the lactobacillus alive, then I could see how having more lactobacillus around wouldn't appreciably change the lactic / acetic acid ratio because metabolic activity is being constrained by food provided by the yeast cells, not temperature nor number of bacteria.

My objection to there being less acetic acid (versus lactic) at a lower temperature stemmed from my knowledge that lactobacillus grow faster at higher temperatures, and an article I read that explicitly said you would get more lactic acid in your culture if you grow it at higher temperatures. These data points led me to believe there would be more acetic acid (versus lactic) at lower temperatures.

If the yeast rapidly consume nearly all the nutrients themselves like lordly masters, then dole out meager allocations of maltose to keep the lactobacillus alive, then I could see how having more lactobacillus around wouldn't appreciably change the lactic / acetic acid ratio because metabolic activity is being constrained by food provided by the yeast cells, not temperature nor number of bacteria.

Actually, conventional knowledge about Lactobacillus sanfranciscensis indicates that it produces glucose to help support Candida milleri. Despite subtle symbiosis, there is still a great deal of antagonism though. The antagonism is what keeps typical ratios at 1:100 for sourdough bread. Yeast in any greater quantity will indeed take over under standard conditions. Yeast cells are approximately 66 times the size of their bacterial neighbor.

My objection to there being less acetic acid (versus lactic) at a lower temperature stemmed from my knowledge that lactobacillus grow faster at higher temperatures, and an article I read that explicitly said you would get more lactic acid in your culture if you grow it at higher temperatures. These data points led me to believe there would be more acetic acid (versus lactic) at lower temperatures.

That would be a whole other objection to what you originally stated. "I don't agree with your comment that by lowering the temperature from 33C to 25C less lactic acid is produced." Yeast are also less active at lower temperatures, so levels of both acids will drop, but because it's is a stronger (palate) acid, a drop in acetic acid will be more noticeable. That was the point I was making.

Happy fermenting.

- red.november

EDIT: By the way, how much the two organisms compete for food will depend on what you feed your starter. If all you're giving them is flour, they're on fairly even ground. I have to admit that part of why I mentioned the food source competition is because I have always fed my starter/preferments molasses in order to support healthy growth. L. sanfranciscensis and C. milleri both compete for sucrose. If you're feeding them malt syrup, L. sanfranciscensis will have the upper hand. Perhaps you should try that if you are not already doing so.

Novembercould you post the dough recipe you use with the Better than cream cheese and olive oil. And you recommend using the Caputo 00 for the dough? Thank you for your time and I have enjoyed reading your posts on all the aspects of pizza making.Mystie

Novembercould you post the dough recipe you use with the Better than cream cheese and olive oil. And you recommend using the Caputo 00 for the dough? Thank you for your time and I have enjoyed reading your posts on all the aspects of pizza making.Mystie

I don't usually have dough formulas that are specific to additives like Better Than Cream Cheese. I just add those ingredients in proportion to how much fat or sugar I want in the dough. For instance, if I only want 1% fat in my dough, I would add 5.6% Better Than Cream Cheese. I treat it just like an oil. You can use any preexisting dough formula to see if it's something you like. A formula that I've used extensively can be found here: http://www.pizzamaking.com/forum/index.php/topic,5028.0.html

I haven't recommended using Caputo 00, but I don't recommend against it either. I was simply answering a question about it. Typically you would use Caputo 00 only if you're interested in that kind of crust, usually fermented at room temperature and baked at higher temperatures.

red.novemberIf you would be so kind... I have been reading a lot about fermentation, yeast and it's symbiotic relationship with various bacteria... and am working to nurture my own wild yeast. DH and I both prefer assertively sour bread and a-little-less-so pizza crust. In reading various authors (Ed Wood, Peter Reinhart and others) it seems there is some disagreement on how to develop that sour tang. I don't want it to bite me back, but I want to develop an assertive tang like San Francisco breads. Since I want to use my starter for both bread and pizza crust, what would you suggest as a rule of thumb concerning temperature, possible "...ose" additives, etc for developing a more sour flavor? You have science on your side much moreso than the authors listed above, so thought maybe another opinion would be helpful!

Another thought just occured to me... does whole grain flour make a difference? I have light and dark rye flours as well as KA white whole wheat, but have been using GM AP to get things rolling. Thoughts?

I would recommend a fermentation temperature of 30°C (86°F) if you're trying to get a good balance of acids, but if you're interested in more lactic than acetic, try cooler temperatures for longer periods, and increase the maltose in your dough. If you're interested in more acetic than lactic, aerate the dough more, ferment at temperatures greater than 30°C, and use less (or no) extra maltose. Just as one would expect based on organic chemistry, when oxygen is aplenty, alcohol is oxidized to acetic acid to provide additional energy for the yeast. Lactic acid levels are not affected by the amount of oxygen in the dough to the same degree.

You could also just do what I do from time to time: add lactic or malic acid. If you want to get that sour flavor the old-fashion way, you just have to be patient with your starter.

Any kind of flour or additive that supplies extra micro-nutrients will make a difference. If you plan to create the sour flavor through your starter, I would recommend using something like molasses and/or malt syrup to supply the nutrients though. The added fat in whole grain flour will oxidize over that longer period of time, depriving the yeast of that oxygen. If it's just going to be a preferment, whole grain flour is fine for adding extra micro-nutrients.

red.november,Thanks for the informative reply. From some of my reading, it seems that acetic acid is more volatile and therefore, beyond the pH factor of sourness, is more available to nose and taste buds as a flavor agent. From this, I would assume that if I want more sour bread, I should work to develop the acetic acid over the lactic. Is that a reasonable assumption, or is it too simplistic? One source suggests a 20/80 ratio of acetic/lactic, but, other than sending a sample off to a lab, I have no idea how I would know what the ratio might be, nor do I think I need to get that scientific. I am hoping that my assumption is correct... and I am taking complete notes as to each step in my procedure.

From a study published by the American Society for Microbiology years ago, the average ratio for sourdough is about 1:2.43; acetic:lactic for fully developed bread, and about 1:2.18 for the starter. I wouldn't worry too much about the exact amounts of each. It sounds like what you want may be a bit different from the average sourdough anyway. I would suggest caring for your starter in such a way as to promote bacterial growth by default, taste the results, and if you think it needs more acetic acid, aerate the starter to promote increased acetic acid production.

From this, I would assume that if I want more sour bread, I should work to develop the acetic acid over the lactic.

As I'm sure you are aware, there are different kinds of sour. If you really want to know what ratio to aim for, consider mixing just the acids together to get an idea of what you think tastes best. You can obtain calcium lactate (in place of lactic acid) pretty easily from several places online, and possibly at your local pharmacy or health food store. Acetic acid, of course, can be had in the form of vinegar.

Since the subject of flavor perception comes up a lot on this forum, I'm going to provide a link to one of the most valuable research points of interest available for free (most of the time) on the Internet.